Electric connecting device

ABSTRACT

The invention relates to an electric connecting device, especially for arrangement between a steering wheel and a steering column switch module of a motor vehicle, comprising a stationary housing part and a rotationable housing part which respectively include a connecting unit and enclose at least one spiral-shaped wound-up, flexible electric conductor whose respective end is connected to the connecting unit and which is guided in a reverse-direction loop inside the housing. The conductor is associated with a forced guidance element in a positive fit, engaging the peripheral side of the conductor and resulting in a defined winding or unwinding of the conductor during a rotational movement of the rotationable housing part. The forced guidance element comprises a toothing that engages into the respective recesses in the conductor and may be assigned to the rotatable housing part, the stationary housing part, or both.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority from PCT application numberPCT/DE03/01159, which was filed Apr. 9, 2003; German patent applicationnumber 102 18 391.0, which was filed Apr. 24, 2002; and German patentapplication number 102 26 806.1, which was filed Jun. 15, 2002.

STATEMENT REGARDING FEDERALLY SSPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

THE NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not Applicable

INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISK

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention pertains to an electric connecting device, especially forarrangement between a steering wheel and a steering column switch moduleof a motor vehicle, comprising a stationary housing part and a rotatablehousing part, which respectively include a connecting unit and encloseat least one spiral-shaped wound up flexible electric conductor whoseend is connected to the connecting unit and which is guided in areverse-direction loop inside the housing.

2. Description of Related Art

Connecting devices of this type are used, in particular, for producingan electrical connection between a power source and a gas-operatedimpact protection device of motor vehicles that is arranged in thesteering wheel. In this case, a conductor arranged between thestationary housing part and the rotatable housing part is of such lengththat it can follow approximately three revolutions of the steering wheelin both directions. The flexible conductor widens outwardly when thesteering wheel is turned in one direction from a central position untilit contacts the stationary housing part and contents inwardly when thesteering wheel is turned in the other direction until it contacts therotatable housing part. This uncontrolled widening and contracting ofthe conductor frequently leads to malfunctions.

BRIEF SUMMARY OF THE INVENTION

The invention is based on the objective of developing an electricconnecting device of the initially described type that always operatesreliably when the rotational housing part is turned.

According to the invention, this objective is realized in that a forcedguidance is assigned to the conductor in a positive fit wherein theforced guidance engages on the periphery of the conductor and causes theconductor to unwind and rewind in a defined fashion when the rotatablehousing part is turned.

During this rotational movement, the conductor follows the forcedguidance such that the conductor is wound and unwound in a controlledfashion when the rotatable housing part is turned. In addition, theforced guidance prevents the conductor from rubbing on the housing partssuch that the noise produced by the conductor can be reduced.

In order to ensure a secure retention and guidance of the conductor, theforced guidance according to one embodiment of the invention comprises atoothing that is assigned to the rotatable housing part and engages intorespective recesses arranged in the conductor. The forced guidancepreferably also comprises a toothing that is assigned to the stationaryhousing part. The elasticity and prestress of the conductor that isguided inside the housing in the form of a reverse-direction loop causethe conductor to permanently adjoin the rotatable and stationary housingparts. This ensures that the toothing arranged on the respective housingparts engages into the recesses of the conductor. The toothing ispreferably arranged on the peripheral surfaces of the opposingstationary housing part and/or the rotatable housing part.

The toothing is preferably realized integrally with the respectivelyassigned housing part. The toothing and the corresponding housing partare manufactured together by means of a plastic injection-moldingprocess such that the toothing no longer must be subsequently fixed onthe respective housing parts and the connecting device can bemanufactured cost-efficiently.

In order to provide a forced guidance that reliably prevents anytwisting or tilting of the conductor, the recesses are preferablyarranged centrally in the conductor relative to its height.

In order to compensate for tolerances, the recesses preferably consistof oblong holes that form a perforation in the conductor, into which thenub-shaped teeth engage. The recesses can be produced by means ofpunching, and the design of the respective nub-shaped teeth ensures thatthe conductor is guided such that only little wear occurs.

In order to enable the connecting device to transmit relatively highcurrents, several conductors may be arranged in the housing in the formof layers that lie one on top of another. These conductors arerespectively guided in a forced manner by the toothing engaged with thealigned recesses and provide a relatively large conductive crosssection, for example, for powering the steering wheel heater of a motorvehicle.

It should be understood that the above-described characteristics, aswell as the characteristics yet to be disclosed, are not only suitablefor use in the respectively described combination, but also in differentcombinations. The scope of the present invention is defined by theclaims only.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One embodiment of the invention is described in greater detail belowwith reference to the drawings. Shown are:

FIG. 1, a perspective representation of an electric connecting deviceaccording to the invention;

FIG. 2, an enlarged representation of the detail II according to FIG. 1,and

FIG. 3, a perspective representation of an alternative embodiment of theelectric connecting device according to FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The electric connecting device comprises a housing 1 that essentiallyconsists of a housing part 2 fixed in a (not-shown) steering columnswitch module and a housing part 3 that is rotatable relative to theaforementioned housing part and connected to a (not-shown) steeringwheel. In this case, the steering column switch module with the housingpart 2 fixed therein is arranged on the outer tube of a steering column.An electric conductor 4 is spirally wound up within the housing 1,wherein the electric conductor is of such length that the steering wheelcan be turned by approximately three to four revolutions. The conductor4 is guided within the housing 1 in the form of a reverse-direction loop5 such that the conductor 4 can be realized with a relatively shortlength. A connecting unit for respectively contacting the conductor 4with the on-board network via the steering column switch module and witha plug on the steering wheel is arranged outside the housing 1 on theend of the conductor 4 assigned to the rotatable housing part 3, as wellas on the end of the conductor assigned to the stationary housing part2.

A forced guidance 6 peripherally engages on the conductor 4 in order toensure that the conductor 4 is wound and unwound in controlled fashionwhen the steering wheel is turned. The forced guidance 6 shown in FIGS.1 and 2 comprises a nub-shaped toothing 7 assigned to the stationaryhousing part 2 and a corresponding toothing assigned to the rotatablehousing part 3, wherein the respective toothing engages into recesses 8in the form of oblong holes arranged in the conductor 4. The toothing 7is realized integrally with the respectively assigned housing part 2, 3and located approximately in the center of the conductor 4 relative toits height. Since the conductor 4 is guided in the form of areverse-direction loop 5 and consequently has a certain elasticity orprestress, it peripherally adjoins the stationary housing part 2 as wellas the housing part 3 that is rotatable relative thereto, his ensuresthat the respective toothing 7 engages into the recesses in theconductor 4.

According to FIG. 3, four conductors 4 are accommodated within thehousing 1, wherein each conductor is guided in the form of areverse-direction loop 5. The loops 5 are separated at intervals. Theconductor 4 is wound and unwound on/from the rotatable housing part 3(rotor) in a controlled fashion when the steering wheel is turned,namely due to the fact that the forced guidance 6 is realized in theform of a toothing 7 that is assigned to the rotatable housing part 3and engages into the recesses 8 in the conductor 4 that are realized inthe form of oblong holes. The toothing 7 is designed in the form of atrapezoid in order to securely guide the conductors 4. The guidance ofthe conductors 4 on the stationary housing part 2 is ensured by thepressing force that is generated with the aid of the reverse-directionloops 5 and presses the conductors 4 against the stationary housing part2.

1. An electric connecting device, especially for arrangement between asteering wheel and a steering column switch module of a motor vehicle,comprising a stationary housing part and a rotatable housing part whichrespectively include a connecting unit and enclose at least onespiral-shaped, wound up flexible electric conductor whose respective endis connected to the connecting unit and which is guided in areverse-direction loop inside the housing, wherein a forced guidance isassigned to the conductor in a positive fit, engaging the peripheralside of the conductor and resulting in a defined winding or unwinding ofthe conductor during a rotational movement of the rotational housingpart; wherein the forced guidance comprises a toothing assigned toeither the rotatable housing part, the stationary housing part, or both;and wherein the conductor is guided within the housing in the form of areverse-direction loop so as to bias respective recesses in theconductor into engagement with the toothing.
 2. The connecting deviceaccording to claim 1, wherein the toothing is assigned to the rotatablehousing part.
 3. The connecting device according to claim 1, wherein thetoothing is assigned to the stationary housing part.
 4. The connectingdevice according to claim 1, wherein the toothing is respectivelyarranged on the peripheral surfaces of the opposing stationary housingpart and the rotatable housing part.
 5. The connecting device accordingto claim 1, wherein the toothing is realized integrally with therespectively assigned housing part.
 6. The connecting device accordingto claim 1, wherein the recesses are approximately arranged centrally inthe conductor relative to its height.
 7. The connecting device accordingto claim 1, wherein the recesses are realized in the form of oblongholes that form a perforation in the conductor (4), into which therespective toothing engages.
 8. The connecting device according to claim1, wherein a plurality of conductors are arranged in the housing in theform of layers that lie one on top of another.
 9. The connecting deviceaccording to claim 1, wherein the forced guidance comprises a nub-shapedtoothing.
 10. The connecting device according to claim 1, wherein theforced guidance comprises toothing designed in the form of a trapezoid.